This invention relates generally to ballcock assemblies for controlling the admission of flush fluid, normally water, into the reservoir tank used in connection with toilet bowls, and more particularly, to an improved construction which precludes backflow and/or siphoning of the flush fluid from the reservoir tank into the supply line.
Conventional ballcock assemblies generally consist of a metal inlet tube terminating at its lower end with a threaded mounting shank that extends, in sealed relation, through the bottom wall of a reservoir tank for connection to a water supply line. A ballcock valve mechanism is mounted at the upper end of the inlet tube to be actuated by a lever arm and ball float.
Connections between the several parts of a ballcock assembly, irrespective of the particular material from which they are fabricated, give rise to difficulties in assembly and often result in leakage due to corrosion and/or relative movement between the parts. Moreover, leaks can occur along the span of the various parts so that even if the ballcock is of unitary construction it is not necessarily immune from leakage.
Any leakage which permits the flush fluid to flow into the reservoir tank will, upon the occasion of a drop in the pressure within the supply line, allow the flush fluid stored in the reservoir tank to backflow, or to be siphoned, into the supply line.
Some prior art ballcock assemblies are constructed so that the water level in the reservoir tank can rise above the level of the ballcock valve. Here, too, the fluid source can be contaminated by backflow or siphoning in response to a reduction in the pressure of the fluid within the supply line.